I'd like to replace the countdown counter with a Youtube video.
I noticed that the background image (the beach) fills my complete browser screen and adapts its size if I resize the browser.
That's cool. But when I add a YT player it just sits there at a fixed size.
I noticed that if I create a layoutgrid I could just put a YT player in the middle column of a 3 column grid and it would work as I'd like.
But as far as I can tell there is no way to put a layoutgrid on that first layer.
But when I replace the layer with a grid, it doesn't fill the complete screen like the layer does.
I have the feeling I'm overlooking something, but I don't know what it is.

In the YouTube object select enable 'Fill entire browser window' this will then set the video as a background. This option is also available for Vimeo and HTML5 video.
Example: Video Background Template

Thank you for your reply. Perhaps I didn't explain my goal clearly enough.
I want to put an adaptive player say at 60% of the browser window width on top of the screen filling image (the beach in the example).
For some reason the beach image resizes to accomodate the changing browser size, but the YT player I put inside the layer doesn't adapt its size.
And I can't figure out what I need to change to do this.

If you place a YouTube object inside a layout grid then it will resize automctally.

This I noticed. But I couldn't find a way for that layout grid to be part of the floating layer 'coming soon'.
As far as I could tell, a layout grid doesn't fill a whole screen, because it's adaptive.
I'm trying to get best of both worlds.

I can see two: one with 'video background' with a space image and one with a palm tree and a nice beach video.
I don't think I've managed to make my question clear enough. I don't want a fullscreen video. I want a fullscreen background image (like in the 'coming soon' template) with a Youtube player centered in the browser window that adapts its size if I resize the browser, in the way a layout grid does.
I could send you a Dutch e-mail if it wll help explain things better

If you add a YouTube video to a layout grid then it will be responsive/flexible. There is no the way to make it flexible, because it needs some guidance what its size must be.
A layout grid can also have a background.